The primary study end-point is the recurrence-free survival after study inclusion, and this is defined by the interval between the date of written informed consent until recurrence. Secondary end-points are the overall survival and the surgical complication rate. Interim analyses are performed after the inclusion of 100 and 200 patients without interrupting patient accrual. An independent data monitoring committee will review the results of each interim analysis and will decide about the study cessation or continuation.